1. Field of the Invention
The present invention relates to a ceramic building board, and to the method of manufacturing the ceramic building board. In particular, the present invention relates to a building board which exhibits an excellent color development without relying on coating, and to the method of manufacturing the building board.
2. Description of the Related Arts
With respect to the coloring work for a ceramic building board, xe2x80x9ccoatingxe2x80x9d is popular at present. The coating, however, takes many manufacturing steps, and energy cost required for executing plural drying steps and colorant cost become higher. Further, in plural spray coating steps, scattering loss of colorants and the like are not avoidable. On account of that high coating cost, the final product cost of a ceramic building board inevitably comes so expensive.
Moreover, since organic solvents have been used (in some cases, an aqueous emulsion type colorant is used), work environment is getting worse as an inevitable consequence, and the draining treatment cost additionally comes more expensive.
However, it is forced to use xe2x80x9ccoatingxe2x80x9d in order to express complicated and unique designs on the surface of a ceramic building board.
Incidentally, as a design expressed on the surface of a ceramic building board, those that made up of groove portions and convex portions occupy the majority of surface designs. Greatly reduced coating cost will be expected, if only groove portions of building board can be colored, without relying on coating. Dry forming process is one of the manufacturing processes for building boards where the forming and curing of cement substrate are done, with the quantity of water to be used being limited to as minimum as possible (see Japanese Patent Publications H6-28849, H6-88823 and H7-10582).
Thus, as a way of coloring the groove portions without relying on the coating, there can be an idea that pigments are directly mixed into the raw materials of cement substrate to manufacture a cement building board.
However, an adverse phenomenon called xe2x80x9cefflorescencexe2x80x9d is generated during an autoclave maturing process that is an important heat-treating step in the substrate manufacturing, which obstructs the color development by pigments and hence impairs the coloration of the substrate.
The efflorescence is a white material produced in the following manner: causative components that are included in cement curing materials migrate in the form of an aqueous solution to the surface of the substrates at which they are separated by evaporating water component. The efflorescence contains sodium sulfate, calcium carbonate, potassium sulfate, sodium carbonate, sodium hydrogencarbonate, magnesium sulfate, gypsum, potassium hydroxide, etc.
The present invention is made in view of the above problems and therefore an object of the present invention is to provide a building board which is colored by mixture of pigments into the raw materials and exhibits an excellent color development, and manufacturing method thereof.
Namely, the present invention provides a colored building board comprising front and back layers of high density, whose main components are a wood material(s) and a self-curing inorganic material(s); and a core layer of lower density compared with the front and back layers, whose main components are a wood material(s) and a self-curing inorganic material(s); wherein a pigment(s) and a resin(s), or a pigment(s) and a water-resistant additive(s) are incorporated into at least the front layer among the front and back layers.
Preferably, the above resin(s) is a resin(s) used for mixing with cement.
Further, the above water-resistant additive(s) contains at least one of the materials selected from the group consisting of stearate, calcium acrylate, ammonium oleate, asphalt, paraffin, hydroxyethyl cellulose and maleic acid.
Furthermore, the present invention also provides a colored building board comprising front and back layers of high density, whose main components are a wood material(s) and a self-curing inorganic material(s); and a core layer of lower density compared with the front and back layers, whose main components are a wood material(s) and a self-curing inorganic material(s); wherein at least the front layer among the front and back layers contains a pigment(s) and has a resin film on the surface thereof.
Preferably, the above resin film is a resin used for mixing with cement.
Further, the present invention also provides a colored building board comprising front and back layers of high density, whose main components are a wood material(s) and a self-curing inorganic material(s); and a core layer of lower density compared with the front and back layers, whose main components are a wood material(s) and a self-curing inorganic material(s); wherein at least the front layer among the front and back layers contains a pigment(s) and a anti-efflorescence agent(s).
Preferably, the above anti-efflorescence agent(s) contains at least one of the materials selected from the group consisting of fluoride, carbonate, polyaminocarboxylic acid and maleic acid.
A manufacturing method for manufacturing a colored building board according to the present invention is a dry forming method, wherein a pigment(s) and a resin(s) are incorporated into at least the front layer among said front and back layers to form a resin film simultaneously with cement curing.
Further, a manufacturing method for manufacturing a colored building board according to the present invention is a dry forming method, wherein a pigment(s) and a water-resistant additive(s) are incorporated into at least the front layer among the front and back layers to provide a water-resistant property simultaneously with cement curing.
Furthermore, the above water-resistant additive(s) contains at least one of the materials selected from the group consisting of stearate, calcium acrylate, ammonium oleate, asphalt emulsion, paraffin emulsion, hydroxyethyl cellulose and maleic acid.
Moreover, a manufacturing method for manufacturing a colored building board according to the present invention is a dry forming method, wherein a pigment(s) is incorporated into at least the front layer among the front and back layers, and a resin(s) is coated on a molding board to form a resin film on the surface of the colored building board simultaneously with cement curing.
In addition, a manufacturing method for manufacturing a colored building board according to the present invention is a dry forming method, wherein a pigment(s) is incorporated into at least the front layer among the front and back layers, and a resin(s) is coated on the surface of the cured cement board, and after forming the resin film, the cured cement board is subjected to an autoclave maturing process.
Preferably, the above resin(s) is resin emulsion for mixing with cement.
Further, a manufacturing method for manufacturing a colored building board according to the present invention is a dry forming method, wherein a pigment(s) and a anti-efflorescence agent(s) are incorporated into at least the front layer among the front and back layers, and insoluble salts are generated in the front layer.
Preferably, the above anti-efflorescence agent(s) contains at least one of the materials selected from the group consisting of fluoride, carbonate, polyaminocarboxylic acid and maleic acid.
This specification includes part or all of the contents as disclosed in the specification and/or drawings of Japanese Patent Application No. 21531/2000, which is a priority document of the present application.